The present invention is an improvement over existing shell cutter members for cutting holes in large diameter pipe. Heretofore shell cutter members have been provided with a plurality of teeth silver-soldered to the lower end of the body member and separated by flutes extending upwardly on the body member. In these prior art shell cutter members, which were primarily used for cutting through metallic pipe or asbestos concrete pipe, the chips or shavings cut from the pipe were oftentimes dropped into the pipe. Attempts have been made to obtain "chipless" cutting, these attempts usually taking the route of providing sleeves on the outside of the cutters in a attempt to trap the chips or shavings. The prior attempts at providing "chipless" cutting have resulted in high torque for the operation and they were not effective to completely retain the chips. The flutes used between the teeth of these prior shell cutter members were oftentimes designed to try and direct the chips outwardly of the shell cutter member but even in this type of design, the chips would fall around the exterior of the pipe adjacent the hole and when the shell cutter was removed from the hole in the pipe the chips would fall backwards into the pipe.
In metal pipes where the metal was of a ferrous material or the like and chips did fall into the pipe, magnetic means could be used to clean out the inside of the pipe. This is not true in a situation where plastic pipe is used and thus if any chips did fall into the pipe, such chips could interfere with the operation of equipment downstream of where the hole was being cut, such as in valves or the like.
In U.S. Pat. No. 3,870,431 issued Mar. 11, 1975 to Lawrence F. Luckenbill and Daniel A. Ellis, and assigned to the same assignee as this application, namely, Mueller Co., Decatur, Illinois, there is disclosed a chipless cutter member for cutting holes in small diameter thick or thin wall pipe, the design of the cutter member being such that the chips are directed into the cavity or chamber of a cylindrically shaped metal body member. However, this cutter, while extremely effective when used on small diameter plastic pipe, is not particularly adaptable for large diameter pipes of, for example, 4 inch to 12 inch and greater diameters. In cutting large diameter plastic pipes and obtaining a large diameter hole in the pipe, a large amount of material must be removed from the pipe in addition to the coupon being cut and consequently the design criteria of this prior art cutter member is not adaptable to accommodate the situation with respect to large diameter pipes. Additionally, the torque for rotating and advancing such a cutter member would increase with the size of the hole being cut because the wall of the body member of the cutter member is in frictional contact with the wall of the hole being cut.